This invention relates to molding methods and metal-covered parts formed thereby and, in particular, to molding methods and metal-covered plastic parts formed thereby which are adapted for use on motor vehicles such as partial or entire fascia, and body side moldings and the like which have bright surface requirements.
Many parts such as automotive parts are metal-plated after they are formed. The plating process requires elaborate facilities and consequently necessitates large expenses. For instance, significant square footage of a factory must be dedicated to such an environment for the plating of chrome on components such as those components used in the automotive industry, such as bumpers, bumper guards, side moldings, and the like. Moreover, certain metals have in recent years raised significant environmental concerns. As a result, such metals must be strictly monitored to satisfy environmental and safety regulations.
U.S. Pat. No. 5,626,704 discloses a composite automotive trim strip having a thermoplastic shell secured to the front of a support member.
U.S. Pat. No. 4,999,227 discloses an automotive bumper comprising a shell of injection molded plastic that is plated with chromium metal.
U.S. Pat. No. 5,741,446 discloses a method for producing a molded article, using a mold assembly having a cavity and an insert block formed of ceramic or glass.
U.S. Pat. No. 3,740,918 discloses a decorative trim strip comprising an elongate channel-shaped base molding having a vinyl or plastic decorative trim piece adhesively secured thereto.
U.S. Pat. No. 4,431,711 discloses a corrosion and abuse resistant plastic object that is vacuum metalized with a corrosion prone metal on a dielectric substrate.
U.S. Pat. No. 3,934,385 discloses a trim strip for an automotive body panel having a flexible plastic decorative covering secured to a core.
U.S. Pat. No. 4,902,557 discloses a method and apparatus for manufacturing a thermoplastic polyolefin composite useful as an exterior auto or truck body part. A polyester film is fed through a roll roller coater to apply first a clear coating and then a pigmented coating. A layer of thermoplastic chlorinated polyolefin provides intercoat adhesion of the pigmented layer to a polyolefin resin layer. In other words, a clear coat and then a color coat over the clear coat is applied to a polyester film in the form of Mylar. The resulting coated polyester film is then laminated to a thermoplastic polyolefin sheet. Then the polyester film is stripped off. The resulting face sheet is thermoformed into a shaped structure. This resulting face sheet does not include the stripped off polyester film.
U.S. Pat. No. 5,529,336 discloses a chromed or silvered applique and a plastic liner extruded onto the applique to form a sheet. The sheet is cut to form an applique member which is vacuum-formed. The vacuum-formed member is then insert molded with a plastic base.
U.S. Pat. No. 4,769,100 teaches a method of applying a carrier film pre-printed with metallic paint to an automobile body panel in a vacuum forming process. In other words, the carrier film is applied to automobile body panels in a vacuum forming process wherein a bottom surface of the carrier film is coated with a layer of adhesive.
U.S. Pat. Nos. 4,952,351 and 5,466,412 teach a method of manufacturing an air bag cover for an inflatable air bag system including a bondable film carrier, which is painted after the film carrier is molded.
However, the prior art fails to provide a method of manufacturing a metal-covered component wherein the step of plating the component after molding is eliminated and further where the component has the structural integrity both in terms of durability and strength to support varying applications including vehicle exterior applications.
This application is related to U.S. patent application Ser. No. 09/144,315, filed Aug. 31, 1998, entitled xe2x80x9cFoil Covered Plastic Part and Method of Making Samexe2x80x9d, now issued as U.S. Pat. No. 6,280,823.
Another object of the present invention is to provide a molding method and a metal-covered plastic component formed thereby wherein molding scrap due to minor surface imperfections on the plastic can be reduced by completely covering the surface imperfections by the metal covering.
Yet still another object of the present invention is to provide a molding method and a metal-covered plastic component, such as a partial or entire fascia, body side moldings, and the like, wherein the component has increased durability yet has a bright surface.
In carrying out the above objects and other objects of the present invention a method is provided for manufacturing a metal-covered, molded plastic component. The method includes providing a film sheet having a decorative layer of metal. The film sheet is selected from the group consisting of polyester, polyurethane and polycarbonate. The method further includes forming the film sheet to obtain a preform, and placing the preform in a mold cavity of an injection mold having a shape defining the desired plastic component. The method also includes injecting a thermoplastic elastomer into the mold cavity of the injection mold to generate a structural carrier for the preform. The generation of the structural carrier creates sufficient pressure and heat to bond the structural carrier to a bottom surface of the preform to form the metal-covered molded plastic component. The method finally includes preventing the preform from moving in the mold cavity during the step of injecting.
Preferably, the thermoplastic elastomer is selected from the group consisting essentially of a thermoplastic polyolefin, thermoplastic urethane, polyester, polycarbonate, acrylonitrile/butadiene/styrene, polypropylene, lomod, bexloy, a mixture of acrylonitrile/butadiene/styrene and polycarbonate, and mixtures thereof.
Also, preferably, the step of injecting a thermoplastic elastomer into the mold cavity occurs at a temperature of approximately 420xc2x0 F. and at a pressure of 50 psi to 15,000 psi.
The method may include the step of cutting the preform prior to the step of placing.
The structural carrier may have a flexural modulus in the range of 15,000 to 400,000 psi.
The structural carrier may have a durometer in the range of 15 Shore D to 100 Shore D.
The film sheet preferably has a total thickness of approximately 0.2 mils.
Further in carrying out the above objects and other objects of the present invention, a method of manufacturing a metal-covered, molded laminate automotive component is provided. The method includes inserting a film sheet having a decorative layer of metal into a forming station to form the film sheet into a predetermined automotive component shape to create a formed film sheet having top and bottom surfaces. The film sheet is selected from the group consisting of polyester, polyurethane and polycarbonate. The method further includes placing the formed film sheet in a mold cavity of an injection mold having a shape defining the automotive component. The method also includes injecting a thermoplastic elastomer into the mold cavity of the injection mold, such that the thermoplastic elastomer is in mating contact with the bottom surface of the formed film sheet, to generate a structural carrier for the formed film sheet. The generation of the structural carrier creates sufficient pressure and heat to bond the structural carrier to the bottom surface of the formed film sheet to form the metal-covered, molded laminate automotive component. The preform is prevented from moving in the mold cavity during the step of injecting.
Still further in carrying out the above objects and other objects of the invention, a method of manufacturing a metal-covered, molded plastic component is provided. The method includes providing a film sheet having a decorative layer of metal. The film sheet is selected from the group consisting of polyester, polyurethane and polycarbonate. The method further includes forming the film sheet to obtain a preform and placing the preform in a mold cavity of an injection mold having a shape defining the desired plastic component. The method also includes injecting a thermoplastic elastomer into the mold cavity of the injection mold to generate a structural carrier for the preform. The generation of the structural carrier creates sufficient pressure and heat to bond the structural carrier to the bottom surface of the preform to form the molded laminate plastic component wherein the decorative layer of metal is coated with polyvinylidine fluoride and a clear plastic layer.
The polyvinylidine fluoride may comprise more than 50% of the total thickness of the film sheet.
The thermoplastic elastomer may be selected from the group consisting of a thermoplastic polyolefin, thermoplastic urethane, polyester, polycarbonate, acrylonitrile/butadiene/styrene, polypropylene, a mixture of acrylonitrile/butadiene/styrene and polycarbonate, and mixtures thereof.
The step of injecting a thermoplastic elastomer into the mold cavity may occur at a temperature of approximately 420xc2x0 F. and at a pressure of 50 psi to 15,000 psi.
The method may include the step of cutting the preform prior to the step of placing.
The structural carrier may have a flexural modulus in the range of 15,000 to 400,000 psi.
The structural carrier may have a durometer in the range of 15 Shore D to 100 Shore D.
The film sheet may have a total thickness of approximately 0.2 mils.
Still further in carrying out the above objects and other objects of the invention, a method of manufacturing a metal-covered, molded laminate automotive component is provided. The method includes inserting a film sheet having a decorative layer of metal into a forming station to form the film sheet into a predetermined automotive component shape to create a formed film sheet having top and bottom surfaces. The film sheet is selected from the group consisting of polyester, polyurethane and polycarbonate. The method further includes placing the formed film sheet in a mold cavity of an injection mold having a shape defining the automotive component. The method also includes injecting a thermoplastic elastomer into the mold cavity of the injection mold, such that the thermoplastic elastomer is in mating contact with a bottom surface of the formed film sheet to generate a structural carrier for the formed film sheet. The generation of the structural carrier creates sufficient pressure and heat to bond the structural carrier to the bottom surface of the formed film sheet to form the molded laminate automotive component. The decorative layer of metal is coated with a layer of polyvinylidine fluoride and a clear plastic layer.
The polyvinylidine fluoride may comprise more than 50% of the total thickness of the film sheet.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.